Some units are defined under symbols from the COMMON-LISP package ("second",
"tenth", …). In some implementations (ECL, CLISP), this triggers a package lock
error, because those symbols cannot be re-exported in the COMMON-LISP package.

New function state-value-expand will create a form to compute the
desired functions in the state value. It is more efficient to use this
expansion in code (say from a macro) when the "have" quantities are
known at compile time, because this avoids function construction at run
time.

If equal-dimension is called with errorp=T and two grids that do not
have the same dimension and at least one had non-scalar-dimension,
signal an error. Previously, this would just return NIL NIL even though
errorp is T.
References
[[id:a456e075-1746-454d-b68c-ad6fa21fb293][Zero in matrix-from-columns can't be added]]
[[id:39fe9321-7260-4335-bb3e-735ba1d00e43][Alternative approach to mixed/scalar pq-grid]]

The function now named test-grid is very useful for the testing the
correct construction of all kinds of grids. Checking formatting was the
original purpose but the purpose has grown beyond that. Eventually, this
function should be relocated.

Because atan has only one mandatory (specializible) argument, the
numerator, the denominator cannot be specialized, so (number
physical-quantity) caused an error. This is fixed with an :around method
loaded with physical-quantities that will coerce the numerator to the
same dimensions as the denominator (units will be the system of units
for that dimension).

When conversion to UT1 was attempted but *real-ut1-utc* was NIL, the
result was a timepoint that had the original dtspec value but whose
scale was set to :ut1. This has been fixed by returning two values from
convert-utc-ut1, the second value being a success indicator, which is
used by convert-time-scale to to determine how to set the scale on the
timepoint.

Prior code was redefining the # dispatching macro character.
This would obliterate the prior dispatch character definitions on CCL
including standard ones such as #C(...) #( )
I removed this particular statement. Antik looked fine after that.

Added "Getting Started" chapter to the documentation. Generated
LaTeX/PDF form of Sphinx documentation. Added definition so that
(asdf:test-system :antik) will work, and tests both ANTIK and GRID
packages.

Antik no longer rebinds *read-default-float-format*. If it is 'single-float, there could be some unexpected precision loss when parsing time intervals, so it is rebound to 'double-float for reading times. The seconds part of timeparse can now be a rational. If it's an integer, the time interval will be formatted as an integer for output. If it's a rational, the time interval will be coerced to a double float.

In order to avoid potential conflict with other programs,
*read-default-float-format* is not set. Instead, a new function
#'set-reader will make the Antik reader macros active in the listener
and set *read-default-float-format*.